feat(web): report page views via sendBeacon and show stats on system page

reaction_board/web/static/app.js

@@ -1,4 +1,4 @@
-import { session } from "./api.js";
+import { session, visit } from "./api.js";
 import { disposeAll } from "./charts.js";
 import { onRoute, parseLocation, startRouter } from "./router.js";
 import { renderCandidates } from "./views/candidates.js";
@@ -153,9 +153,15 @@ async function boot() {
     toast("无法连接看板服务", "error");
   }
   renderNav();
+  let lastVisitPath = null;
   onRoute(({ path, route }) => {
     disposeAll();
     setTitle(route, path);
+    // 访问统计：仅在路由路径变化时上报（排序/筛选等同路径重渲染不计 PV）。
+    if (path !== lastVisitPath) {
+      lastVisitPath = path;
+      visit(path);
+    }
   });
   startRouter({
     root: document.querySelector("#app"),